Horn speaker

ABSTRACT

A horn speaker includes a speaker housing with a diaphragm suspended therein to form an air chamber in the rear of the housing. Conventional magnetic voice coil structure is responsive to input electrical signals for vibrating the diaphragm to generate acoustic energy. A speaker horn is connected to the speaker housing for transmitting the acoustic energy generated by the diaphragm. A tube communicates at one end with the air chamber and at the other end with the front portion of the speaker horn in order to equalize the pressure on opposite sides of the diaphragm. A rubber film is applied to the diaphragm suspension to increase the structural strength thereof.

United States Patent lnventor Francis A. Miller Lawton, Okla. Appl. No. 827,322 Filed May 23, 1969 Patented Feb. 16, 1971 Assignee Ben 0. Key

Lawton, Okla. a part interest HORN SPEAKER 6 Claims, 3 Drawing Figs.

1 V 181/27 lnt.Cl ,l 0kl3/00,,

- 1-l04r 1/28 Field ofSearch 181/27,31, 31.1, 31A, 32

Primary ExaminerStephen J. Tomsky Attorney-Richards, Harris & Hubbard ABSTRACT: A horn speaker includes a speaker housing with a diaphragm suspended therein to form an air chamber in the rear of the housing. Conventional magnetic voice coil structure is responsive to input electrical signals for vibrating the diaphragm to generate acoustic energy. A speaker horn is connected to the speaker housing for transmitting the acoustic energy generated by thediaphragm. A tube communicates at one end with the air chamber and at the other end with the front portion of the speaker horn in order to equalize the pressure on opposite sides of the diaphragm. A rubber film is applied to the diaphragm suspension to increase the structural strength thereof.

. M; Feb. 16,1971 V 3,563,336

INVENTO'R .FRANCIS A. MILLER ATTORNEY HORN SPEAKER FIELD OF THEINVENTION THE PRIOR ART Horn-type speakers have been used for some time for higher frequency acoustic sound generation. Particularly useful is the dome radiator type of horn speaker, wherein a thin metallic foil diaphragm is supported about. the periphery to form a reverse dome structure opening outwardly toward a speaker horn. The reverse dome structure supports voice coils and is surrounded by a conventional permanent magnet such that input electrical signals cause vibration of the diaphragm and cause the emission of sound through the speaker horn.

However, such previously developed dome radiator speakers have been subject to shattering and breakage during operation or handling, due to the fact that a sealed air chamber has been formed between the reverse dome structure and the rear portion of the speaker housing. Changes in the ambient pressure have thus often caused a severe pressure differential across the diaphragm, often causing shattering, cracking or other damage to the diaphragm.

SUMMARY OF THE INVENTION In accordance with the present invention, an improvement is made in horn speakers having an air chamber adjacent a suspended speaker diaphragm by providing an air passageway communicating between the air chamber and a forward portion of the speaker horn. The air passageway allows the pressure on opposite sides of the speaker diaphragm to remain equalized.

In accordance with another aspect of the invention, a diaphragm is suspended within a speaker housing to form an air chamber in the rear of the housing. Structure is provided for vibrating the diaphragm in response to electrical input signals. A speaker horn is connected to the housing for transmitting acoustic energy generated by vibration of thediaphragm. Structure provides air communication between the air chamber and the speaker horn in order to equalize the pressure on opposite sides of the diaphragm to prevent breakage thereof.

In accordance with a more specific aspect of the invention, a length of tube is connected at one end to the air chamber formed in the rear of a horn speaker housing and at the other end to the speaker horn in order to" equalize the pressure on the speaker diaphragm. The length of the tube is at least equal to one wavelength of the low cutoff frequency of the speaker.

In accordance with another aspectof the invention, a vibratable dome diaphragm is suspended within a speaker housing by an annular suspension member. A thin coating of silicone rubber is bonded to one side of the suspension member for increasing the structural strength of the diaphragm to prevent cracking and other breakage.

DESCRIPTION OF THE-DRAWINGS For a more complete understanding of the present invention and for other objects and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 somewhat diagrammatically illustrates a typical dome radiator horn-type speaker designated generally by the numeral 10. The speaker comprises a speaker housing 12 including an annular rear cover 14. Bolts 16ad, some of which are omitted for simplicity of illustration, connect a plastic ring 18 to the housing 12. An annular suspension member 20 is connected at its outer edges to the plastic ring 18 and supports at its center a vibratable dome diaphragm 22. As shown in FIG. 2, in the preferred embodiment the suspension member 20 comprises crimped metal foil, while the dome diaphragm 22 comprises thin metallic aluminum foil or the like. A speaker or voice coil 24 is formed about the outer edge of the diaphragm 22. A suitable construction for the speaker coil 24 is a wound copper ribbon. A permanent magnet 26 surrounds the voice coil 24 in the conventional manner. A speaker horn 28 is connected to housing 12 for transmission of sound generated by diaphragm 22.

An important aspect of the invention is the small tube 30 which is connected at one end 32 for communication with the air chamber 33 defined between the diaphragm 22 and the annular cover 14. The other end 34 of tube 30 communicates with a forward portion 28a of the speaker horn 28. Tube 30 equalizes the air pressure on opposite sides of the diaphragm 22.

Horn speaker 10 operates in the well-known manner wherein input electrical signals applied to the voice coil 24 cause vibration of the diaphragm 22 and the diaphragm suspension 20. This vibration of the diaphragm causes the generation of acoustic energy which is fed from the speaker housing 12 outwardly through the horn speaker 28.

The present invention is applicable to any one of a number of horn-type speakers wherein normally a sealed air chamber is defined between the vibratable diaphragm and the rear of the speaker housing. In particular, the invention is advantageous for use with dome radiator-type horns of the type illustrated. As an example, the present invention may be advantageously utilized with the speaker driver system type 802D or 806A in combination with a speaker horn type 5118 or 811B, each of which is manufactured and sold by Altec- Lansing Corporation of Anaheim, California.

To modify such speakers according to the invention, an aperture is made in the walls of the cover 14 and one end 32 of a tube 30 is connected thereto. An aperture is then made in the forward portion of the speaker horn 28 and the opposite end 34 of the tube 30 is affixed thereto. Thistube provides pressure communication between the rear air chamber and with the front of the horn speaker. Thus, sudden changes in I the ambient pressure in the vicinity of the horn cannot damage FIG. 1 is a partially sectioned view of a typical dome radia- I the diaphragm. Additionally, provision of the air passageway from the rear of the horn to the front portion of the horn as illustrated in FIG. 1 provides improved power handling capabilities for the horn, as well as increasing the lifetime of the horn diaphragm.

In the preferred embodimentof the invention, the tube 30 is constructed from a small plastic tube made from nylon or the like. For optimum performance, it is important that the length of the tube 30 be equal to or greater than one wavelength of the minimum operating frequency of the horn, or of the low frequency cutoff of the horn. For instance, with a horn having a 600 cycle per second cutoff, the length of the tube 30 would be about l8 inches. For such a length of tube 30, an 18 gauge inside diameter tube has been found advantageous in practice. Additionally, for optimum operation of the invention, the end 34 of the tube 30 should be placed as close as possible to the mouth of the speaker horn 28.

Another aspect of the invention which assists in increasing the lifetime of the speaker 10 is illustrated in FIG. 3. As previously noted, in conventional dome-type radiators such as the Altec-Lansing speakers previously identified, the diaphragm suspensions 20 comprise crimped annular metal foil. According to this invention, a thin layer 40 of silicone rubber, or the it will thus be seen that the present invention substantially increases the useful lifetime of dome-type radiator speakers without impairing the acoustic performance thereof. Further, the addition of the air passageway between the front and back air columns of such a hom-type speaker provides acoustical advantages in increasing the speaker capacity to handle power. The provision of the tube 30, along with the addition of the rubberized compound 40, has been found in practice to substantially eliminate problems in shattering or breakage of the speaker diaphragms.

Whereas the present invention has been described with respect to a specific embodiment thereof, it will be understood that various changes and modifications will be suggested to one skilled in the art, and it is intended to encompass such changes and modifications as fall within the scope of the appended claims.

lclaim:

l. A speaker which comprises:

a speaker housing;

a diaphragm suspended in the housing and forming an air chamber within the housing to the rear of the diaphragm; a horn connected to the housing and acoustically coupled to the front of the diaphragm, the horn having a forward portion extending from the housing; and means'forming an air passageway communicating between the air chamber and the forward portion of the horn. 2. The combination of claim 1 wherein the last mentioned is a tube interconnecting the first mentioned means and the horn.

3. The combination of claim 2 wherein the tube has a length greater than one wavelength of the minimum operating frequency of the speaker. i

4. in a speaker, the combination comprising: a speaker housing; a diaphragm suspended within the housing and forming an air chamber in the rear of said housing; means for vibrating the diaphragm in response to electrical signals; a horn connected to the housing for transmitting acoustic energy generated by said diaphragm; the horn having a forward portion extending from the housing; and means for providing air communication between said air chamber and the forward portion of the horn for equalizing the pressure on opposite sides of the diaphragm. 5. The combination of claim 4, wherein the means for providing air communication comprises:

a tube opening at one end into the air chamber and at the other end into the forward portion of the horn. 6. The combination of claim 5 wherein one end of the tube is connected adjacent the front end of the horn. 

1. A speaker which comprises: a speaker housing; a diaphragm suspended in the housing and forming an air chamber within the housing to the rear of the diaphragm; a horn connected to the housing and acoustically coupled to the front of the diaphragm, the horn having a forward portion extending from the housing; and means forming an air passageway communicating between the air chamber and the forward portion of the horn.
 2. The combination of claim 1 wherein the last mentioned is a tube interconnecting the first mentioned means and the horn.
 3. The combination of claim 2 wherein the tube has a length greater than one wavelength of the minimum operating frequency of the speaker.
 4. In a speaker, the combination comprising: a speaker housing; a diaphragm suspended within the housing and forming an air chamber in the rear of said housing; means for vibrating the diaphragm in response to electrical signals; a horn connected to the housing for transmitting acoustic energy generated by said diaphragm; the horn having a forward portion extending from the housing; and means for providing air communication between said air chamber and the forward portion of the horn for equalizing the pressure on opposite sides of the diaphragm.
 5. The combination of claim 4, wherein the means for providing air communication comprises: a tube opening at one end into the air chamber and at the other end into the forward portion of the horn.
 6. The combination of claim 5 wherein one end of the tube is connected adjacent the front end of the horn. 